The present invention is based on a device for wireless transmission of a trigger signal, in particular for a restraint system.
From European published, unexamined patent application 616 924 A1, a device and a method for wireless transmission and transmission of power are known heretofore. Data transfer from a primary side to the secondary side is carried out during a short interrupt at a primary-side breaker gap during the energy storage phase; data transfer in the reverse direction is carried out via a secondary-side load pulse during the energy storage phase.
By contrast, the device according to the present invention for wireless transmission of a trigger signal, in particular for a restraint system, has the advantage that the redundancy ensures additional reliability with respect to erroneous triggering. In particular in the case of restraint systems this ensures increased reliability with respect to erroneous triggering of an airbag.
It is particularly advantageous that the enable unit on the secondary side switches the evaluation unit over to a status where it is ready to receive the trigger signal, and preferably an interrupt is used for this. Thus a kind of xe2x80x9cpreliminary stagexe2x80x9d in the trigger signal is achieved via the redundancy signal that activates the enable unit, so that the actual trigger signal is received reliably by the evaluation unit on the secondary side. This ensures increased reliability with respect to receiving of the trigger signal.
Furthermore, it is useful that the redundancy signal is carried out via switching over of the frequency and/or level of the signals to be transmitted via the transmitter. As a result, this redundancy signal can be evaluated in a straightforward manner on the secondary side.
Furthermore, it is useful that in addition to the trigger signal diagnostic signals and control signals, in particular for the restraint system, can be transmitted via the transmitter. This transmission is interrupted for the trigger signal, so that the trigger signal is prioritized over the diagnostic and/or control signals. This also allows better use to be made of this transmission path, and means transmission of the trigger signal is more reliable.
Furthermore, it is useful that the transmitter is either inductive or capacitive, depending on the application. The transmitter may also be optical. In this case, both the data and the power are transmitted optically between the steering wheel and the steering column.
Moreover, it is useful that the trigger circuit triggers at least one ignition circuit having at least one airbag, if necessary a seat-belt tensioning device as well as the ignition circuits and air bags being also triggered by the trigger circuit.
Furthermore, it is useful that the redundancy unit has a trigger command detector, a pulse generator, and/or a level switch-over unit. As a result, if a trigger signal is detected, either a pulse train and/or an increased level is generated as the redundancy signal. Both forms of signalxe2x80x94a pulse train and an increased levelxe2x80x94can be detected on the secondary side in a straightforward manner. Furthermore, it is useful that the enable unit has a pulse counter and/or a comparator for the level, and a status circuit for triggering the secondary-side evaluation unit. As a result, the enable unit can evaluate the pulse train and/or the increased level and can activate the trigger circuit using the monoflop. The status circuit is used to activate the secondary-side evaluation unit so that it is ready to receive the trigger signal.
Furthermore, it is useful that the primary side 13 of the device according to the present invention is arranged in a steering column 501 or vehicle floor 502, and the secondary side 7 is arranged in a steering wheel 503 and/or a vehicle seat 504, as shown in FIG. 5. Herein, it is also useful that the components on the primary side 13 are arranged in a housing, e.g., as identified by reference numeral 100 in FIGS. 1 and 4, and if necessary are integrated into a control device for the restraint systems.